1、BRITISH STANDARD BS 6955-15: 1994 ISO 5347-15: 1993 Calibration of vibration and shock pick-ups Part 15: Method of test for acoustic sensitivity UDC 534.1:681.327.7:53.089.6BS6955-15:1994 This British Standard, having been prepared under the directionof the General Mechanical Engineering Standards P
2、olicy Committee,waspublished underthe authority of theStandards Board andcomesintoeffect on 15March1994 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference GME/21 Draft for comment 87/72304 DC ISBN 0 580 23087 2 Committees responsible for this British St
3、andard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Policy Committee (GME/-) to Technical Committee GME/21, upon which the following bodies were represented: Electricity Association Federation of Civil Engineering Contractors Imperial College
4、 of Science and Technology Institute of Sound and Vibration Research Institution of Mechanical Engineers Lloyds Register of Shipping Ministry of Defence Open University Power Generation Contractors Association PGCA (BEAMA Ltd.) Railway Industry Association of Great Britain Sira Test and Certificatio
5、n Ltd. Society of British Aerospace Companies Limited The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Coal Corporation Health and Safety Executive Society of Environmental Engineers University of Cranfield Amendments issued since
6、publication Amd. No. Date CommentsBS6955-15:1994 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Apparatus 1 3 Method 1BS6955-15:1994 ii BSI 11-1999 National foreword This Part of BS 6955 has been prepared under the direction of the General Mech
7、anical Engineering Standards Policy Committee. It is identical with ISO5347-15:1993 Methods for the calibration of vibration and shock pick-ups Part 15: Testing of acoustic sensitivity, published by the International Organization for Standardization (ISO). ISO 5347-15 was prepared by Technical Commi
8、ttee ISO/TC 108, Mechanical vibration and shock, in which the UK played an active part. BS 6955 consists of the following Parts, which are identical with the corresponding Parts of ISO 5347: Part 0: Guide to basic principles; Part 1: Methods for primary vibration calibration by laser interferometry;
9、 Part 2: Method for primary shock calibration by light cutting; Part 3: Method for secondary vibration calibration; Part 4: Method for secondary shock calibration; Part 5: Method for calibration by Earths gravitation; Part 6:Method for primary vibration calibration at low frequencies; Part 7: Method
10、s for primary calibration by centrifuge; Part 8: Method for primary calibration by dual centrifuge; Part 9: Method for secondary vibration calibration by comparison of phase angles; Part 10: Method for primary calibration by high impact shocks; Part 11: Method of test for transverse vibration sensit
11、ivity; Part 12: Method of test for transverse shock sensitivity; Part 13: Method of test for base strain sensitivity; Part 14: Method of test for resonance frequency of undamped accelerometers on a steel block; Part 15: Method of test for acoustic sensitivity; Part 16: Method of test for mounting to
12、rque sensitivity; Part 17: Method of test for fixed temperature sensitivity; Part 18: Method of test for transient temperature sensitivity; Part 19: Method of test for magnetic field sensitivity. Part 20 of ISO 5347 is in preparation. It is envisaged that when it is published it will be implemented
13、as Part 20 of BS 6955. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages T
14、his document comprises a front cover, an inside front cover, pages i and ii, page1and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6955-15:1994 BSI 11-1999 1 1 Sco
15、pe ISO 5347 comprises a series of documents dealing with methods for the calibration of vibration and shock pick-ups. This part of ISO 5347 lays down detailed specifications for the instrumentation and procedure to be used for acoustic sensitivity testing. It applies to accelerometers. This part of
16、ISO 5347 is applicable for a frequency range of random noise from 125 Hz to 8000 Hz and a sound pressure level of 130 dB (referencevalue:2 10 5 Pa). 2 Apparatus 2.1 Equipment capable of maintaining room temperature at 23 C 3 C. 2.2 Room, having a volume of at least 75m 3so as to obtain approximate f
17、ree-field conditions. 2.3 Random noise generator, low-pass filter or equalizer, amplifier and loudspeaker, which can produce a free-field random noise with a total sound pressure level of 130 dB 5 dB (referencevalue:2 10 5 Pa) with the following spectrum shape per frequency octave band: 125Hz: 115 d
18、B 6dB; 250 Hz to 2000 Hz: 120 dB 5 dB; 4000Hz: 115 dB 6 dB; 8000Hz: 105 dB 10 dB. NOTE 1A 0,5 mH and 1 4F low-pass filter, a commercial 30 W power amplifier and an 8 in, 50 W broadband loudspeaker in a1m 1 m baffle is recommended. Distance from the loudspeaker to the accelerometer: 50 mm to 100 mm.
19、2.4 Sound level measuring equipment with octave band filtering, covering the range from 80 dB to140dB (referencevalue:2 10 5 Pa) and with uncertainty maximum 3 dB. 3 Method 3.1 Test procedure Place the loudspeaker in the middle of the room with no hard reflecting surfaces in front of it. Suspend the
20、 accelerometer in a rubber harness in front of and close to the loudspeaker. The suspension resonance frequency shall be lower than20 Hz. Rotate the accelerometer in order to find maximum sensitivity. Replace the accelerometer by a microphone and shape the noise spectrum. After the accelerometer has
21、 been suspended in its rubber harness and then rotated, measure the maximum output, in metres per second squared, for the specified sound pressure level. If it is suspected that whole accelerometer rigid body vibrations are induced and that this affects the accelerometer output, special test procedu
22、res, outlined in 3.3, shall be carried out and reported. 3.2 Expression of results The acoustic sensitivity shall be reported as the equivalent accelerometer output, in metres per second squared, for the applied level sound pressure (referencevalue:2 10 5 Pa). 3.3 Special test procedures Acoustic se
23、nsitivity measurements of piezoelectric accelerometers can be difficult to make because whole rigid body vibratory motion effects can be induced into the accelerometer. If these effects are suspected, the following methods for minimizing motion effects shall be applied: a) Mount the accelerometer on
24、 a very heavy but small fixture; this generally distorts the acoustic field so the sound pressure level has to be measured with the microphone in an accelerometer dummy mounted on the fixture. b) Measure the induced motion with an accelerometer that is protected and mounted inside the fixture and su
25、btract the induced motion components from the pick-up output. c) Mount the accelerometer on the smallest possible rod fixture clamped to a heavy base and isolate this fixture and the base from the sound field; a high density material, e.g. tungsten, is recommended.BS 6955-15: 1994 ISO5347-15: 1993 B
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